A surface acoustic wave device includes a piezoelectric substrate, functional elements on the piezoelectric substrate, a cover portion that opposes the piezoelectric substrate with a support layer interposed therebetween, and an input/output terminal on the cover portion. At least a portion of the functional elements includes an interdigital transducer electrode, and a surface acoustic wave resonator is defined by the piezoelectric substrate and the IDT electrode. The functional elements include a filter that passes a signal in a predetermined frequency band, and a cancel circuit which is connected in parallel to the filter and attenuates a signal outside the predetermined frequency band in signals output from the output terminal. A portion of a wiring pattern connecting a first functional element and a second functional element included in the plurality of functional elements is provided on the cover portion.

A surface acoustic wave device includes a piezoelectric substrate, functional elements on the piezoelectric substrate, a cover portion that opposes the piezoelectric substrate with a support layer interposed therebetween, and an input/output terminal on the cover portion. At least a portion of the functional elements includes an interdigital transducer electrode, and a surface acoustic wave resonator is defined by the piezoelectric substrate and the IDT electrode. The functional elements include a filter that passes a signal in a predetermined frequency band, and a cancel circuit which is connected in parallel to the filter and attenuates a signal outside the predetermined frequency band in signals output from the output terminal. A portion of a wiring pattern connecting a first functional element and a second functional element included in the plurality of functional elements is provided on the cover portion.

A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit is provided between a first terminal and a second terminal. Between the first terminal and the second terminal, the additional circuit is connected in parallel with at least a portion of the transmission filter circuit. The additional circuit includes an IDT electrode group including a plurality of IDT electrodes located next to each other in an acoustic wave propagation direction and two reflectors that sandwich the IDT electrode group and having different numbers of pairs of electrode fingers.

A transmission filter includes a transmission filter circuit and an additional circuit. The transmission filter circuit is provided between a first terminal and a second terminal. Between the first terminal and the second terminal, the additional circuit is connected in parallel with at least a portion of the transmission filter circuit. The additional circuit includes an IDT electrode group including a plurality of IDT electrodes located next to each other in an acoustic wave propagation direction and two reflectors that sandwich the IDT electrode group and having different numbers of pairs of electrode fingers.

Aspects of this disclosure relate to acoustic wave filters that include different types of acoustic wave resonators for series resonators and shunt resonators. In certain embodiments, an acoustic wave filter includes series temperature compensated surface acoustic wave resonators and shunt bulk acoustic wave resonators. Such an acoustic wave filter can be a band pass filter.

Aspects of this disclosure relate to acoustic wave filters that include different types of acoustic wave resonators for series resonators and shunt resonators. In certain embodiments, an acoustic filter component includes a first die including surface acoustic wave resonators and a second die including bulk acoustic wave resonators. An interdigital transducer electrode of a surface acoustic wave resonator can be a side of the first die. An electrode of a bulk acoustic wave resonator can be on a side of the second die facing the side of the first die with the interdigital transducer electrode thereon. An acoustic wave filter can include series resonators on one of the first and second die and shunt resonators on the other of the first and second die.

Aspects of this disclosure relate to acoustic wave filters that include different types of acoustic wave resonators for series resonators and shunt resonators. In certain embodiments, an acoustic filter component includes a first die including surface acoustic wave resonators and a second die including bulk acoustic wave resonators. An interdigital transducer electrode of a surface acoustic wave resonator can be a side of the first die. An electrode of a bulk acoustic wave resonator can be on a side of the second die facing the side of the first die with the interdigital transducer electrode thereon. An acoustic wave filter can include series resonators on one of the first and second die and shunt resonators on the other of the first and second die.

A surface acoustic wave device includes a piezoelectric substrate and functional elements on a first surface of the piezoelectric substrate. At least a portion of the functional elements includes an interdigital transducer (IDT) electrode, and a surface acoustic wave resonator is defined by the piezoelectric substrate and the IDT electrode. A portion of a wiring pattern connecting a first functional element and a second functional element is on a second surface different from the first surface of the piezoelectric substrate.

A surface acoustic wave device includes a piezoelectric substrate and functional elements on a first surface of the piezoelectric substrate. At least a portion of the functional elements includes an interdigital transducer (IDT) electrode, and a surface acoustic wave resonator is defined by the piezoelectric substrate and the IDT electrode. A portion of a wiring pattern connecting a first functional element and a second functional element is on a second surface different from the first surface of the piezoelectric substrate.

A filter device according to an embodiment of the present disclosure includes a first filter and a second filter that are connected in parallel between a first terminal and a second terminal. The first filter includes multiple series arm resonators. The series arm resonators are disposed in series in a path from the first terminal via the first filter to the second terminal. The series arm resonators include a first series arm resonator and a second series arm resonator. Under a condition that a value obtained by dividing a difference between an antiresonance frequency and a resonance frequency of each series arm resonator by the resonance frequency is defined as a fractional bandwidth, a first fractional bandwidth of the first series arm resonator is different from a second fractional bandwidth of the second series arm resonator.